how do you test an ignition coil

easiest is substitution

could you hold it about the spark plug and see if it spark ?

Usually on a scanner it will tell you which one has died and simply replace.

Nedavno sleeper napisa:

Perhaps you could measure resistance with ohmmeter. For my car (BMW) primary resistance is 0.82 ohm (measured at terminals 1 and 15, or - and +), and secondary resistance is 8250 ohm (measured at center tower and 15 or +). I have - TCI Transistorized Coil Ignition. On BMW E30 models with Motoronic ignition system values are 0.50 ohms for the primary and 5000 ohm's for the secondary.

Perhaps you can find the values for your car on the Internet, or someone here might help.

When the op cannot even put a simple detail like the make and model there is little hope!

Those are good basic steps, but won't prove absolutely that a coil is good.

For example, there may be internal insulation breakdowns from secondary to case, or between primary and secondary. There may be some shorted turns, more likely in the secondary winding, that still leave the resistance values within specification. There may be an internal intermittent connection fault.

The only reliable test from a DIY perspective is substitution.

Chris

Nedavno Mrcheerful napisa:

Talking about ignition coils, I have one question too. How do you test Ford Edis coil pack like this one here:

I got mine at a wrecks from ford escort (I do not knew what year was it, but I guess it was around 92-95).

It's a wasted spark coil pack (you get spark on two cylinders at the same time). There are three terminals. I measured between middle and left (and right) one, and it's OK. So primary is OK (both of them).

But if I connect at any HT lead connection point and any of the terminals for the primary, or a metal (where bolts are on the photo in a link above) - nothing is shown on my ohmmeter. I tried all possible combinations.

So is my coil pack fried, or am I doing something wrong?

You test the secondary across TWO ht leads, NOT to earth

One spark is positive, one negative (out of general interest)

Nedavno Mrcheerful napisa:

OK, thank you. It's 0.8 ohm for the primary, and 13.3 Kohm mesured across two HT leads for the secondary. Does that sound right?

those are fine. a typical reading for a ford coil is : 0.4 - 0.6 primary and 10.5k - 16.5 k for the secondary

Nedavno Mrcheerful napisa:

OK. Now I just have to fabricate 36-1 trigger wheel, so that I can test if the electronic EDIS module works, and then to order MegaJolt Lite Jr here:

I hope it performs better than my current ignition system :-)

Thank you.